Answer: c. +4
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here manganese is having an oxidation state of +4 called as cation and oxygen forms an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged to give 
which written in simplest whole number ratios to give neutral 
Answer:
The answer would be Point of Reference.
In order to determine, whether an object has moved or not, a point of reference is required. The reference point is required to the measure the movement of the object, without a reference point the distance or displacement cannot be obtained. Hence, a reference point is very required to determine, whether the object has moved or not.
(Hope this helps) Sky
Answer: (3) silicon
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Silicon (Si)
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: ethane 
, propanone 
and water 
Yes because obviously some other organism lives off eating that organism so if they die off the other organisms will be affected heavily
